Multi-service switches/routers are well known in the art and are widely deployed as access points to multi-protocol label switching (MPLS) networks. Multi-service switches/routers must carry many different types of traffic including: Frame Relay; Asynchronous Transfer Mode (ATM); Internet Protocol Version 4 (IPv4); Internet Protocol Version 6 (IPv6); Virtual Wire; etc.
FIG. 1 is a schematic diagram illustrating an exemplary architecture of a prior art multi-service switch/router 10. A plurality of links 12 provide input/output (I/O) channels over which network traffic of various types is carried. The links 12 are connected to a plurality of Media Adapter Modules 14, only four of which are shown: 14a, 14b, 14c, and 14d. The Media Adapter Modules 14 are in turn connected to one or more payload processing and queuing units 16, only two of which are shown: 16a and 16b. Both the Media Adapter Modules 14 and the payload processing and queuing units 16 perform many complex functions, as will be explained below with reference to FIG. 3. Each payload processing and queuing unit 16 is connected to a switch fabric 18 which functions in a manner well known in the art to transfer payload traffic between the payload processing and queuing units 16.
FIG. 2 is a schematic diagram of a plurality of the multi-service switches/routers 10 configured to provide access service to a Multiprotocol Label Switched (MPLS) network 20. Only four of the multi-service switches/routers are shown: 10a, 10b, 10c and 10d. As can be seen, the multi-service switches/routers 10 can accept input in a plurality of different transport protocols, such as: Asynchronous Transfer Mode (ATM); Frame Relay (FR); Ethernet; Packet over Sonet (PoS); Point-to-Point Protocol (PPP); MultiLink ATM; MultiLink FR; MultiLink PPP; and others.
In order to handle the many different transport protocols and traffic types, multi-service switches/routers are becoming more complex. To provide reliable multi-layer functionality, such as dependable Layer 3 Quality-of-Service (QoS) in conjunction with dependable Layer 2 QoS, different congestion points within a switch/router are required. When a traffic flow traverses two or more congestion points within the switch/router it is desirable to maintain consistent discard and throughput statistics for the traffic. This permits users to easily identify how much traffic is dropped within the switch/router, and how much traffic is successfully delivered, without a requirement for additional statistics correlation equipment. There are many prior art mechanisms such as Netflow® and Cflowd® that are used in routers to monitor and report Internet Protocol (IP) packet flows. However, those mechanisms are not designed to deal with different types of traffic and cannot be used to maintain consistent flow statistics if there are multiple congestion points within a multi-service switch or router.
Since multi-service switches/routers carry many different types of traffic, correlation of discards can be difficult to achieve at multiple congestion points. This is especially true when traffic is translated into different encapsulation formats as it traverses a switch/router. Currently, it is frequently left to a “billing agent” to correlate discards at various layers on a switch/router. Billing agents are generally complex and often require a stand-alone application and/or a network element that adds capital and operational expenses for network operators.
It is therefore highly desirable to provide a method of collecting consistent flow statistics through multiple congestion points within a multi-service switch/router.